NEW YORK (CNN/Money) -
Labor groups trying not to let Wal-Mart steal the spotlight this week denounced the retailer's business practices Monday, a day before Wal-Mart kicks off a two-day media event at its Arkansas headquarters.

"The company is having a huge impact on our public health system," Georgia state Rep. Nan Grogan Orrock said during a news conference sponsored by the AFL-CIO, the nation's biggest labor group. "There is quite an alarming reaction when taxpayers learn they are footing the health insurance bill for Wal-Mart employees."

Orrock said Wal-Mart's health insurance plans are so expensive or provide such thin coverage that thousands of children in Georgia end up on the state's health insurance plan.

But criticism wasn't limited to just health coverage. Former and current employees attacked the company's wage and promotion system, which they said was discriminatory, and labor activists said the retailer receives more than $1 billion a year in a variety of government subsidies.

'What Wal-Mart does is drive small business out of business," said Marvin McMickle, a reverend and community leader who was active in an anti-Wal-Mart campaign in the Cleveland area. "And they provide relatively low wages with limited benefits."

A Wal-Mart spokeswoman, responding in a prepared statement to questions sent in advance, said the AFL-CIO charges are "yet another desperate attempt to recycle misinformation" and said Tuesday's media event is an effort for reporters to get the truth about Wal-Mart.

The company has defended its business practices in the past, saying it pays its workers around $10 an hour, nearly twice the federal minimum wage, and that Wal-Mart's low prices provide significant savings -- and hence more disposable income -- for millions of Americans.

Wal-Mart (Research) is holding a two day media event at its headquarters in northwest Arkansas Tuesday and Wednesday.

The conference, a rarity for the company, is seen as an attempt to foster better relations with the media after a number of public setbacks for the retailer.

The company has been hit with dozens of lawsuits alleging sexual discrimination and practices which shortchange employees out of pay. It has also settled charges it contracted illegal alien workers.

The firm also continues to face opposition for community groups when it tries to enter some cities and towns.

The company last year announced it was overhauling its pay and promotion policies.

Wal-Mart, which for the fourth year in a row topped the Fortune 500 list of America's largest companies ranked by sales, is the biggest private sector non-union employer with 1.5 million workers.

The retailer has been fighting union attempts to organize its stores for years, with workers at a Colorado branch recently rejecting a proposal to unionize shortly after Wal-Mart closed a store in Canada where workers had voted to unionize and were still trying to negotiate a first contract.